Rotary cutting tool



H. P. GER.

RY CUTTI ,L.

,ED AUGJ I 91 Feb. 20, 1923;

a SHEETS-SHEET' 1.

Afs .Warn w Feb. 20, v19.23. 1,446,342.

H'. P. GERDIL.

ROTARY CUTTIN L.

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3 SHEETS-SHEET 2 Feb.. 20,1923..

-H. P. GEHDIL.

ROTARY CUTTING TooL. FILED AUG.13| 19l9.

v3 SHEETS-SHEET a.

kf; 14H0 my Fatented Feb. 2d, i923.

STATES `y nenni rnosrnn ennnin, or Panis, FRANCE.

ROTARY CUTTING TOOL.

Application filed August 13, 1919. Serial AINowl'Qli.

To @ZZ whom t may @mice/fn.'

Fe it known that fl, HENRI Pnosrnn Gane nin, a citizen of the Frenchltepiliblic, residing at 7 Rue Gustave Nadaud, Faris,in the Republic ofFrance, haveinvented new and useful improvements in Rotary CuttingrFools, of which the followingis a specification.

This invention relates to `improvements.in rotary cutting` tools usedfoi' iworling any materials.

@ne important feature ofthe invention consists in the fact thatthe-toolcomprises support-ingsurfaces with respect to which the cutting'edges forni a very'reducedprojection, so that in case of `bendingof thetool, the latter iinds support by said surfaces on the wallof theincision made by the tool in the piece. i

Other features of the invention will be described further on.

ln `the annexed `drawings `givenfby way of example:

Fig'. l is a cross section of iaitwobladed tool constructed according'to the invention.

Figs. 2 and 3 are views of a tool respectively in'ovided withtransverse, and `helicoidal supporting ribs.

Fig. et illustrates avtool provided with interrupted transversesupportingl ribs.

F igs. 5 and 6 arerespectively a view in elevation and a view in crosssection1 on line lr-B of Fig;- 5, of a toolof whichthe cutting edges andsupporting; ysurfaces are` titions of which are provided with notches.`

Fig. l2'is a cross sectionfof a tool with straight blades without acore. i

Fig. 13 is a sectionof alike tool with curved blades. y

l shows the application of the invention to a rotary tool which can besupposedl pivoted by its ends in a support and which is fed laterally inthe direction of the arrow in orderto make 1t cut into the piece offwoodA (tree,'etc.) with a view to cut-` tingat up or makingafmortisetherein, the

width of said piece being `less than the length of theftool. flhecylindricalcorel ofthe tool carries `twoblades. i

`Said bladesare secured tothe corebyany desired means. rilwo chipreceiving slots or grooves lbyare formediin-the core in front ofthecutting edges. In order to enable the toolto frest lduring the operationuponthe` Wall ot'` the cut formed in thework whilefat the sametinieavoiding' an excessive friction the tool is provided, according totheinven-r tion `with*transverse circular ribs 3 which project from `thecore by a suitable distance. Such 4ribs rare also shown in `2. The ribsmay be otherwisearranged. i

Fig. 3 shows spiral ribs 3l. s

"lhe ribs neednot necessarily loe-continuous they can be interruptedfandcomposed otl parts arranged y in aline or distributed i in any way. Fig.ashows interrupted'ribs 8.

These points of support, like theribscan be cut in the core or fixedthereto; they could also be elastic. y

The number ofthe ribs and their dimensions varyY according' tothe`kindvof toolfitls workT lthe material-to be worked, etc. They must benear enough-together forguidance tojbe ensured androne of them at leasttobe engam'ed yin ythe incision, Their width depends above all onthehardness of thenia# terial tothe workedpit must .be sumcientto opposepenetration. inally their height7 that is to^say l the differenceof'radiusfbetween'theirouter surface andthe surface of the core, may beextremely variable, -also friction must vbe avoided without .funnecessarily weakening the core.`

TWhen ithpefcutting edgesiare y'cut in the tool bodyVtheribshave`another important advantage. T he edg'efmust alwaysproject withoutthere being heeling. The projection diniinishingat each sharpening wouldend by quickly disappearing, This leadsto diminishing' the core atthesainetiine that the `edge is sharpened. This lengthy and diiiiicultwork issimplitied by means lofthe ribs, which it is suiiieient tofgrindor tile. At long' intervals the core hollowe'd out againfbetween theribs without troublingvto strictly .respect its outline. ln thisycaselthe ribs inust he rather deep.

*Figa 5 shows in elevation and Fig'. 6 in cross sect-ion on'the lineier-Blof Fig. 5 a

tool l oft-his hind with two spiral cutting edges 11, 12. 'Ihis tool isshaped as if it were to possess four cutting edges 9, 10, 11, 12. Two ofthese edges, 9 and 10, alternating with the others, are then so workedas to do away with the cutting-edge and reduce their diameter by somemillimetres so that the circle described by their apices is found to bewithin the circle of the cutting edges 11, 12. These edges 9, 10 fulfillthe function of spiral ribs and the cutting edges can be worn awaywithout it being necessary to hollow out the core afresh. AThisconstruction would apply to toolswith 6, 8, 10, etc., edges. It is notnecessary for the pitch of the ribs to be the same as that of thecutting edges.

In the case of one-edged tools for boring or two-edged ones for cuttingoff or mortis` ing, the guiding can be improved by giving a greaterdiameter to certain parts of the ribs.

Fig. 7 represents the cross section of a tool 1 with one edge.r Assuming13a to be the circumference described by one point of the cutting edge18 lof the blade 2 and 3 the circle corresponding to the periphery ofthe ribs 3. When the tool is at work it tends to bend until the ribscome to bear at a, on the wall of the hole. To obvia-te'this bending theribs can be excentered, that is to say, given a greater height in thepart situated on the left of 7),' that is toy say, in the Zone oppositethe blade, as shown at 14.

Fig. 8 represents the cross section of a tool 1 with two edges 23, 24,engaged in a mortise, shown at 17, 18 being assumed to be thecircumference described by a point of the cutting edges, land 19 that ofthe ribs 8. When the active edge is nea-r the point 24 the tool can benduntil the rib catches at 21 on the wall of the mortise 17, and a spacecapable of attaining double the extent of the projection is producedinthe zone e y.

These fieXions can be corrected by giving the ribs a greater diameter intwo places c d and e f, placed symmetrically and the axis `of which isfound on the perpendicular 21, 22 to the diameter 23, 2,4, uniting thetwo edges asindicated at 14. 'Ihe circumferential development and theheight of the raised portions depend on the material to be worked, onthel speed and the rate of feed, etc. n In. order to avoid jamming thehigh and low parts of the ribs are oined by slightcurves 25 and 26.

To reduce friction, the tool and especially the top of the ribs shouldbe polished; all

roughnesses should be removed and all angles tending to tear thematerial. In particular, behind the sloping edge of the blade theangular edge should be omitted and the core connected to the blade by acurve.

The chip receiving groove or slot might inconveniently discontinue thecircular outline of the tool which would not be properly guided. This isremedied by partitioning the groove. Opposite the ribs 3 or elsewhere(Fig. 9) partitions 36, 37 arey provided which form a bridge between thetwo lips of the notch or groove 32 and form circular supportingsurfaces. Fig. 9 represents a groove with three partitions 36 37situated in alignment with the ribs. These partitions, the number ofwhich need not correspond with that of the-rib, can be cut in the coreor joined thereto andy may be solid orhollow; their side surface can beparallel as indicated at 37, or sloped as indicated at 36, so as to endin a point in frontl of the cutting edge.

Figure 10 shows how the joined on blades 2 are secured; the core isprovided with slits 50 which leave between them and the blades parts ofmaterial or tongues 51 having a certain mobility. By means of conicscrews, screwswith countersunk heads, or the like 52, which are screwedinto the core, these tongues 51 are pushed back against theblades,sothat the latter are solidly held in place by friction. The tongues 51could also be separate from the core.

Inasmuch as chipsniight get inserted between the knife and thepartition, the edge can be interrupted in front of the partition. Inthis case the partitions in the different grooves must be staggered inorder that the material left by one knife may be removed by thefollowing ones. A small notch `can also be made in the partition, justunder the cutting edge, so as to provide a space where theshaving-,although piled up, can still be lodged. having partitionsprovided with this small groove or notch 38. The lateral edges must beconnected to the groove by rounded parts in order to avoid"stuiiings. Y

In this construction the blades 1 are secured by means of wedges 53 held'by screws 54.

The tool can also have no core. Inthis particular case the partitionsassume great importance; they connect the two knives by forming spacers.Fig. 12 represents a tool of this kind having two straight blades 39separated by the partitions L11y forming spacing members and acting asribs for supporting the tool against the workpthe outer edges of -thesepartitions being circular. Counter-plates l2 with circular outer facesand acting also as ribs are fixed to the partitions ll1 by screws 13extending through the knives. The 'counter-plates lf2 can also bedispensed with. Fig.A 13 shows a tool of this kind with curved blades110. In operation. the tool will rest in its rotation yupon lthe wall ofthe cut formed in the work by means of the circular outer edge of thepartitions a1, and of the blades 410.

A tool could also be constructed on the saine principle, with onestraight or curved Fig, 11 represents a special tool,`

blade, the partitions of which would be still further extendedin orderto complete the circle and replacing one oit the two ribs.

ln the cutting oli and mortising, il the speed is low, it the shaving islight, it the cutting in is deep and it obstacles are niet with on theedges (fringes, burrs, etc.) the ejection is insuliicient; the shavingsaccumulate in the cut-out section behind lthe tool, so that the latterwhen rotating not only is not ijlisengaged trom the shavings but bringsthem back, again cutting or chewing them and reducing them to powder.This inconve'nience is wholly or partially moderated owing to thepartitions of which the number is multiplied, the groove is then iilledwith more difficulty.

rl`he invention is applicable to any known rotary cutting tools. Theknown rotary cutting tools can be improved, such as mortising drills,eye-drills, milling cutters, sinking and carving tools, rabbeting andgrooving tools, variously shaped t'ools, circular planes, reamers,scraping and bleaching tools, etc.

The improved rotary chisels and cutting tools can be used for thecutting off, shearing, mortising, sinking, milling, moulding, dressing,rough-dressing, boring, etc., ot all solids.

having now described my invention what l claim as new and desire tosecure by Letters Patent is:

l. A rotary cutting tool comprising a cutter having a cutting edge, acutter carrying member and thin ribs on said cutter carrying member,said ribs having their blunt outer iace slightly back of the surface ot'revolution described by the cutting edge in its rotation, said ribsbeing at an angle with the said surface of revolution, distributedsubstantially along the Whole length of the cutting edge and bearingexclusively upon the wall of the cut formed in the work, said ribs beingarranged in such a manner that there is always at least one rib incontact with the wall ot the cut formed in the work.

2. A rotary cutting tool, comprising a cutter having a cutting edge, acutter carrying member and thin ribs on said cutter carrying member,said ribs having their blunt outer tace slightly back of the surface ofrevolution described by the cutting edge in its rotation, said ribsbeing at an angle with the said surface ot' revolution, distributedsubstantially along the whole length of the cutting edge and bearingexclusively upon the wall of the cut formed in the work, said ribs beingarranged in such a manner that there is always at least one rib incontact with the wall ot' the cut formed in the work, said ribs beingformed of separate sections having a reduced length.

3. A rotary cutting tool comprising a cutter having a cutting edge, acutter carrying member affording a passage 'for the chips, and thin ribson said cutter carrying member, said ribs having their blunt outer :taceslightly back ot the surface ot revolution described by the cutting edgein its rotation, said ribs being at an angle with the said sur- `tace otrevolution, distributedsubstantially along the whole length of thecutting edge and bearing exclusively upon the wall ofthe .cut termed inthe work, said ribs being arranged in such manner that there is alwaysat least one rib in contact with the wall of the cut formed in the work,said ribs extending across the passage 'for the chips.

ln testimony whereof l have signed my name to this specification.

HENBl PROSPER GERDIL.

